School of Electrical, Computer and Energy Engineering
PhD Final Oral Defense
Fabrication and Characterization of Metallic Cavity Nanolasers
by
Kang Ding
April 18 2014
9:00 am
Goldwater Center 409
Committee:
Dr. Cun-Zheng Ning (chair)
Dr. Hongbin Yu
Dr. Joseph Palais
Dr. Yong-Hang Zhang
Abstract
In this thesis, I present my research work in the fabrication and characterization of
metallic cavity nanolasers. Nanolasers represents the research frontier in both the areas of
photonics and nanotechnology for its interesting properties in low dimension physics and
its appealing prospects in integrated photonics and other on-chip applications. By using
low loss metals such as silver, which is highly reflective at near infrared, light can be
confined in an ultra small cavity or waveguide with sub-wavelength dimensions.
Based on this idea, I fabricated metallic cavity nanolasers with rectangular and
circular geometries with InGaAs as the gain material and silver as the metallic shell
serving as cavity. The lasing wavelength is around 1.55 μm, intended for optical
communication applications. Continuous wave (CW) lasing at cryogenic temperature
under current injection was achieved on devices with deep sub-wavelength physical
cavity volume smaller than 0.2 λ3. With improved fabrication process and device design,
CW lasing at room temperature was demonstrated as well on a sub-wavelength
rectangular device with a physical cavity volume = 0.67 λ3. I also demonstrated
experimentally that a small circular nanolasers supporting TE01 mode can generate
anazimuthal polarized laser beam, providing a compact such source under electrical
injection. Such sources could have many special applications. I also studied the digital
modulation of metallic nanolasers, showingthat the laser noise is an important limiting
factor that will affect the data rate of the nanolaser when used as the light source in
optical interconnects.
Due to its ultra-small size, fabrication of such nanolaser and its coupling to external
waveguide are extremely challenging. For future development, improving device
fabrication process for improved device performance and developing the techniques to
realize nanolaser-Si waveguide integration will be the two critical aspects to finally
enable practical applications of such metallic cavity nanolasers.